1. Field of the Invention
The present invention relates to a registration compensation system for a multi-tube color television camera.
2. Description of the Prior Art
In a multi-tube color television camera having a plurality of image pick-up means, for example, of the tri-tube type in which three image pick-up tubes are employed for providing red, green and blue signals, or of the bi-tube type in which two image pick-up tubes are employed for providing luminance and chroma signals, extremely complex controls are necessary for achieving registration of the respective image pick-up tubes. In general, the beam deflecting currents are corrected so as to align the central positions of the output images of the respective image pick-up tubes. However, it is difficult to correct the registration errors which are caused by differences within each image pick-up tube, such as, image rotation (rotation of the image with respect to the axis), distortions (trapezoidal distortion, pincushion distortion or the like) at the periphery of the screen, and errors in image size, scanning linearity, skew distortion and so on. Conventionally, in order to compensate for such registration errors, a complex control circuit generates various control signals to control the beam deflecting currents of the respective image pick-up tubes. Furthermore, since the factors contributing to the registration errors are closely interrelated, registration adjustment at one point on the screen may result in a registration error at another point on the screen. This has made it difficult to achieve uniform registration over the entire area of the screen.